The last thing that more than 70% of British adults do before they go to bed is check social network sites, figures show.

Instead of curling up with a good book before nodding off, 72% of adults check status updates on Facebook, a study conducted on behalf of Travelodge found.

The questionnaire, involving 6,000 adults, also found that 18% of them send a daily night-time tweet to their followers.

The average amount of time spent on social networks while between the sheets is 16 minutes.

And experts have warned the online activity performed from bed is affecting people's sleep.

Sleep specialist Dr Michael Hastings, a researcher for the Medical Research Council at Addenbrooke's Hospital in Cambridgeshire, said: "It's having a huge negative effect on people's sleep. Adults don't realise what impact using computers, mobile phones and other gadgets before falling sleep is having on their night's sleep.

"Being exposed to bright light from computer and mobile phone screens while in bed completely delays the brain and body's ability to get to sleep. As a result, people are not able to get to sleep as quickly as they should and aren't getting the required amount of sleep they need each night."

The research also found that as well as social networking, a quarter of Britons do their weekly grocery shopping between the sheets.

One in 10 adults settles any outstanding bills online before nodding off and 35% of people catch up on the latest celebrity gossip.

It also found that alarm clocks are set to become obsolete, with 84% of adults now using their mobile phone to wake themselves up in the mornings.